For over 200 years, the dental root canal procedure has been done using root canal files, which are tiny tapered drills sized according to the size and shape of the canal in order to remove mostly necrotic tissues while enlarging the canal walls to prepare it for obturation, tissue dissolving chemicals, disinfection, and drying. These files are inserted into the canal after the pulp chamber has been accessed and the canal's orifice has been discovered. The cleaning procedure is executed by pushing, rotating, and pulling the file containing debris out, while irrigating with dissolving chemicals such as sodium hypochlorite and EDTA to assist with softening and dissolving the tissues. This cleaning procedure is repeated with a different file sizes and finalized by dissolving the smear layer, which contains debris such as tissue and bacteria, to uncover the dentine tubules. The tubules may also be contaminated, so they also need to be disinfected in order to prevent a retreatment in the future, i.e., the major criteria for a successful treatment.
This traditional procedure has many disadvantages and risks, such as broken file left inside the canal, wall perforation, tooth cracking, and chemical poisoning. Even though advanced tools, such as rotary and retractable activators are in use, files and chemicals still end up being used inside the canal. In addition, the use of a drill or bur causes a disturbing sound that causes patient anxiety.
In addition, cavity preparation often requires removing healthy tooth structures to reach hidden or hard to reach cavity formations, resulting in a weaker tooth structure. In cleaning a cavity with a bur, if the pulp chamber is penetrated a root canal procedure becomes necessary. Removing as little healthy tooth structure as possible is desirable.